The present invention relates generally to skating. More particularly, disclosed herein is a skate with two or more front wheels that pivot relative to a skate frame for improving the efficiency of each skating stroke while extending each stroke""s effective length.
In-line skates of the prior art typically comprise a plurality of rotatable wheels fixed in place in a common line relative to a skate boot that receives a skater""s foot. The wheels normally have a common tangent such that all wheels will contact a flat surface when the in-line skate rests thereon. With such a construction, a skater will tend to be propelled in a given direction by orienting the skate transverse to the desired direction of travel and applying a lateral driving force to the skate primarily with the skater""s leg muscles.
As one knowledgeable in the art will be aware, propulsion is most effectively achieved when the plurality of wheels of the in-line skate are all in contact with the ground surface on which the skater is propelled. With a plurality of wheels in contact with the ground, the leg enjoys a stability that allows it to drive with virtually unlimited force with little or no effort required for stabilizing the skate.
However, the experienced skater will be aware that it is substantially impossible for a skater to keep all wheels of such an in-line skate in contact with the ground surface over the entire skating stroke. Doing so is particularly problematic during the final phase of leg extension. As the leg enters its final stage, the rear wheels of the skate inevitably will follow the skater""s heel in lifting off of the ground surface. With this, since the wheels are fixed in position relative to the skater""s foot, only the foremost wheel remains in contact with the ground whereby it becomes the skaters only means of applying a driving force to the ground. This is plainly evidenced by the uneven wear that the wheels of the in-line skate typically exhibit wherein the foremost wheel normally demands replacement well before the useful lifetime of the rear wheels has expired.
Unfortunately, the effects of a skater""s being unable to keep all wheels in contact with the ground over the entire skating stroke go well beyond mere uneven wheel wear. What for most will be considered a far more important repercussion is that a skater is resultantly unable to transmit all available energy from the skater""s leg to the ground surface. Instead, as the rear wheels are lifted off the ground and only the front wheel remains in contact with the ground for driving the skater, stabilizing the skater""s leg, and enabling other performance characteristics required for most effective propulsion.
Similar disadvantages have been addressed relative to ice skates, for example, by designing blades with convex formal edges so that an increased blade surface will have contact with an ice surface at the end of the skating stroke. Furthermore, ice skates have been developed that allow a pivoting of the skate blade relative to the skate boot about an axis adjacent the toe end of the skate whereby the skate blade exhibits improved contact with the ice surface over final phase of leg extension. As one knowledgeable regarding the sport of speed skating will be well aware, this construction has proven to be a decided advantage over prior art fixed blade constructions.
However, attempting to produce a convex blade profile with in-line skate wheels would require superfluous weight in wheels that would have only relatively minimal contact with the ground. Also, the convex wheel distribution would be easily upset with the rapid wearing typical of skate wheels and the uneven surfaces over which in-line skates must travel. Furthermore, attempting to provide an in-line skate with an all-wheel pivoting blade structure has proven to be unacceptable due to vibrations, undesirable weight and leg stress, and unmanageably complex mechanical requirements.
Advantageously, a number of inventors have endeavored to provide an in-line skate that overcomes these disadvantages. For example, U.S. Pat. No. 4,272,090 was granted to Wheat in 1981 for an in-line skate that has a pivoting front wheel bogie and a fixed rear wheel unit mounted separately to a shoe portion of the skate. The front wheel bogie is disclosed as having an axis of rotation located horizontally at a mid-portion of the skate and vertically well below the bottom of the shoe portion of the skate. With this, the skate is said to provide stable floor contact of the wheels on the front bogie even while the heel and thus the rear wheel unit of the skate is raised from the ground as would happen during the final portion of the skating stroke.
Another in-line skate designed with similar intention is disclosed in the 1997 U.S. Pat. No. 5,634,648 to Tonel et al. In this skate, a front body is rotatably coupled to a rear body, and a pair of wheels is rigidly coupled to each of the front and rear bodies. With this, during the final phase of the skating stroke, the front body will rotate relative to the rear body to allow the front pair of wheels to maintain contact with the ground thereby improving the skater""s comfortability and the effectiveness of the skating stroke.
It must be recognized that these and other skating inventions certainly represent improvements in the art of in-line skating. For a number of reasons, however, even skates embodying these inventions are less than ideal. For example, by disposing the axis of rotation of the front wheel bogie horizontally at the mid portion of the skate and vertically displaced below the bottom of the shoe portion of the skate, skates such as the skate of the ""090 patent compromise the effective length of the skating stroke. The rearward horizontal location of the axis of rotation of the front wheel bogie naturally results in the front wheels being disposed posteriorly along the skate from the outset. With this, the skating stroke is abbreviated. Furthermore, the vertically displaced location of the bogie""s axis of rotation cause it to rotate rearwardly relative to the shoe portion of the skate during the final portion of the skating stroke whereby the front wheels move even farther back relative to the shoe portion thereby further abbreviating and reducing the effectiveness of the skating stroke.
Also, skates such as that disclosed in the ""648 patent that have pivoting boot sections sacrifice the rigidity of the skate structure that is desirable for full force transmission from the skater""s leg, through the skate, and to the ground. With this, energy is lost and most efficient propulsion is compromised. Furthermore, the pivoting boot structure is undesirably complex and vulnerable to wear and breakage.
In light of the foregoing, it is clear that there remains a need in the art for an in-line skate that overcomes the disadvantages of the prior art by providing a skate that enables optimal propulsion over an extended skating stroke.
Advantageously, the present invention sets forth with the broadly stated object of providing an in-line skate that solves each of the problems left by the prior art while providing a number of heretofore unrealized advantages.
Stated more particularly, a principal object of the present invention is to provide an in-line skate that provides an extended skating stroke.
A further object of the invention is to provide an in-line skate that provides for an efficient transmission of force from a skater""s leg to the ground on which the skater is propelled.
Still another object of the invention is to provide an in-line skate that is exceedingly simple yet lightweight in construction.
Certainly these and further objects and advantages of the present invention will be obvious both to one who reviews the present specification and drawings and to one who has an opportunity to make use of an embodiment of the present invention.
In accomplishing the aforementioned objects, an embodiment of the present invention essentially comprises a main skate frame with an anterior end and a posterior end; a carriage frame pivotally coupled to the skate frame; a plurality of wheels comprising a pivoting wheel group rotatably coupled to the carriage frame; and at least one wheel comprising a fixed wheel group rotatably coupled to the main skate frame. Under this arrangement, the pivoting wheel group can pivot with the carriage frame relative to the main skate frame to maintain contact with a ground surface throughout a range of pivoting of the main skate frame relative to the ground surface. Of course, a skate boot with an anterior end, a posterior end, a sole, and an open inner volume of a given length for receiving a skater""s foot may be coupled to the skate frame.
Advantageously, the present inventor has discovered that moving the pivot axis of the carriage frame forward along the length of the skate will lengthen and improve the effectiveness of the skating stroke. With this, the horizontal position of the pivot axis preferably will be anterior to the center of the first metatarsophalangeal joint of the plantar area of the foot. Research has determined that the center of the first metatarsophalangeal joint typically will be approximately three-tenths of the length of the foot from the tip of the person""s big toe. Even more preferably, the pivot axis will be aligned with or anterior to the anterior end of the skate boot whereby the skating stroke will be even further lengthened and improved.
Although manipulating the horizontal position of the pivot axis surely provides for an improved in-line skate, the inventor has further discovered that manipulation of the vertical location of the pivot axis also provides for added advantage. For example, by locating the pivot axis immediately adjacent to the sole of the skate boot, the present invention minimizes the tendency of the pivot axis to move backwardly when the main skate frame is rotated relative to a ground surface. Furthermore, this tendency can be substantially eliminated by locating the pivot axis approximately coincident with the sole of the skate boot. Indeed, the present inventor has discovered that locating the pivot axis distal to the sole of the skate boot relative to the wheels of the in-line skate will reverse this undesirable tendency whereby the pivot axis of the carriage frame will actually move forwardly when the main skate frame is rotated as the posterior end of the main skate frame is lifted from the ground while the anterior end of the frame tends to stay in contact with the ground.
In certain alternative embodiments, the enlarged portion and the elevated retaining plateau can be eliminated while still having the in-line skate enjoy an effective pivot axis in a desired location. To do so, the carriage frame can be pivotally coupled to the skate body by a pivoting mechanism that enables the carriage frame to pivot above an effective pivot axis that is physically displaced from the pivoting mechanism. With such a construction, the carriage frame can pivot about a predetermined effective pivot axis without requiring the pivoting mechanism to be located at the effective pivot axis.
The pivoting mechanism could pursue a number of embodiments. For example, a first embodiment incorporates a first curved surface, which may comprise an external curve, that is fixedly associated with the skate body that is in relatively slidable contact with a second curved surface, which may comprise an internal curve, that is fixedly associated with the carriage frame. Under this arrangement, the first and second curved surfaces can slide relative to one another to allow the carriage frame to pivot relative to the skate body. Even more advantageously, the first and second curves could be interlocked by a pair of engaging shoulders on, for example, the first curved surface in combination with a C-channel on, for example, the second curved surface.
In a second embodiment, the pivoting mechanism can comprise a laterally disposed arcuate passage, which may pass through the carriage frame, in combination with a plurality of pivot support rods, which can have first and second ends coupled to first and second pivot support plates and body portions passing through the arcuate passage. There can be three pivot support rods disposed in a triangular relationship with a given effective height, and the arcuate passage can have a width slightly greater than the effective height of the triangle formed by the three pivot support rods. Under this arrangement, the carriage frame can pivot relative to the skate body around an effective pivot axis by having the pivot support rods travel along the arcuate passage.
Advantageously, in either embodiment the location of the effective pivot axis can be manipulated to further the invention""s goals of improving the length and efficiency of a skater""s skating stroke. For example, where first and second curved surfaces are employed, the location of the effective pivot axis can be manipulated by adjustment of the radii of curvature and orientation of the curved surfaces. Similarly, where an arcuate passage is combined with a plurality of pivot support rods, the location of the effective pivot axis can be controlled by a manipulation of the radius of curvature and orientation of the arcuate passage.
One will appreciate that the foregoing discussion merely outlines the more important features of the invention to enable a better understanding of the detailed description that follows and to instill a better appreciation of the inventor""s contribution to the art. Before an embodiment of the invention is explained in detail, it must be made clear that the following details of construction, descriptions of geometry, and illustrations of inventive concepts are mere examples of the many possible manifestations of the invention.